Conventionally, electrical junction boxes are used in automobiles and the like in order for electrical components such as fuses, relays, and the like to be arranged space-efficiently, for example. As such an electrical junction box, an electrical junction box as disclosed in, for example, JP 2008-295263A (Patent Document 1) is known that has a structure in which a cover is externally fitted to a main body provided with a circuit board such as a printed-circuit board, and the main body is accommodated in the cover.
Meanwhile, in view of the demand for downsizing in recent years, an electrical junction box as disclosed in Patent Document 1 is configured such that a cover is externally fitted to a main body with almost no gap, and the outer surface of the main body and the inner surface of the cover face each other with a very small micro-gap.
Therefore, if water enters the cover through, for example, a gap between the open end of the cover and the main body, capillary action may act in the micro-gap between the outer surface of the main body and the inner surface of the cover, and water may deeply enter the cover. Furthermore, there is the risk that the water that has entered the cover reaches the circuit board of the main body, resulting in a short circuit or corrosion of the circuit board.